/**
 * (C) 2010-2022 Alibaba Group Holding Limited.
 * <p>
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.alibaba.datax.common.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import java.security.SecureRandom;

/**
 * DES加解密,支持与delphi交互(字符串编码需统一为UTF-8)
 * 将这个工具类抽取到 common 中，方便后续代码复用
 */
public class DESCipher {
    /**
     * 密钥
     */
    public static final String KEY = "";
    private final static String DES = "DES";
    private static Logger LOGGER = LoggerFactory.getLogger(DESCipher.class);

    /**
     * 加密
     * @param src 明文(字节)
     * @param key 密钥，长度必须是8的倍数
     * @return 密文(字节)
     * @throws Exception
     */
    public static byte[] encrypt(byte[] src, byte[] key) throws Exception {
        // DES算法要求有一个可信任的随机数源
        SecureRandom sr = new SecureRandom();

        // 从原始密匙数据创建DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);

        // 创建一个密匙工厂，然后用它把DESKeySpec转换成
        // 一个SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey securekey = keyFactory.generateSecret(dks);

        // Cipher对象实际完成加密操作
        Cipher cipher = Cipher.getInstance(DES);

        // 用密匙初始化Cipher对象
        cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);

        // 现在，获取数据并加密
        // 正式执行加密操作
        return cipher.doFinal(src);
    }

    /**
     * * 解密
     * * @param src
     * * 密文(字节)
     * * @param key
     * * 密钥，长度必须是8的倍数
     * * @return 明文(字节)
     * * @throws Exception
     */
    public static byte[] decrypt(byte[] src, byte[] key) throws Exception {
        // DES算法要求有一个可信任的随机数源
        SecureRandom sr = new SecureRandom();

        // 从原始密匙数据创建一个DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);

        // 创建一个密匙工厂，然后用它把DESKeySpec对象转换成
        // 一个SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey securekey = keyFactory.generateSecret(dks);

        // Cipher对象实际完成解密操作
        Cipher cipher = Cipher.getInstance(DES);

        // 用密匙初始化Cipher对象
        cipher.init(Cipher.DECRYPT_MODE, securekey, sr);

        // 现在，获取数据并解密
        // 正式执行解密操作
        return cipher.doFinal(src);
    }

    /**
     * 加密
     * @param src * 明文(字节)
     * @return 密文(字节)
     * @throws Exception
     */
    public static byte[] encrypt(byte[] src) throws Exception {
        return encrypt(src, KEY.getBytes());
    }

    /**
     * 解密
     * @param src 密文(字节)
     * @return 明文(字节)
     * @throws Exception
     */
    public static byte[] decrypt(byte[] src) throws Exception {
        return decrypt(src, KEY.getBytes());
    }

    /**
     * 加密
     * @param src 明文(字符串)
     * @return 密文(16进制字符串)
     * @throws Exception
     */
    public final static String encrypt(String src) {
        try {
            return byte2hex(encrypt(src.getBytes(), KEY.getBytes()));
        } catch (Exception e) {
            LOGGER.warn(e.getMessage(), e);
        }
        return null;
    }

    /**
     * 加密
     * @param src 明文(字符串)
     * @param encryptKey 加密用的秘钥
     * @return 密文(16进制字符串)
     * @throws Exception
     */
    public final static String encrypt(String src, String encryptKey) {
        try {
            return byte2hex(encrypt(src.getBytes(), encryptKey.getBytes()));
        } catch (Exception e) {
            LOGGER.warn(e.getMessage(), e);
        }
        return null;
    }

    /**
     * 解密
     * @param src 密文(字符串)
     * @return 明文(字符串)
     * @throws Exception
     */
    public final static String decrypt(String src) {
        try {
            return new String(decrypt(hex2byte(src.getBytes()), KEY.getBytes()));
        } catch (Exception e) {
            LOGGER.warn(e.getMessage(), e);
        }
        return null;
    }

    /**
     * 解密
     * @param src 密文(字符串)
     * @param decryptKey 解密用的秘钥
     * @return 明文(字符串)
     * @throws Exception
     */
    public final static String decrypt(String src, String decryptKey) {
        try {
            return new String(decrypt(hex2byte(src.getBytes()), decryptKey.getBytes()));
        } catch (Exception e) {
            LOGGER.warn(e.getMessage(), e);
        }
        return null;
    }

    /**
     * 加密
     * @param src
     * 明文(字节)
     * @return 密文(16进制字符串)
     * @throws Exception
     */
    public static String encryptToString(byte[] src) throws Exception {
        return encrypt(new String(src));
    }

    /**
     * 解密
     * @param src 密文(字节)
     * @return 明文(字符串)
     * @throws Exception
     */
    public static String decryptToString(byte[] src) throws Exception {
        return decrypt(new String(src));
    }

    public static String byte2hex(byte[] b) {
        String hs = "";
        String stmp = "";
        for (int n = 0; n < b.length; n++) {
            stmp = (Integer.toHexString(b[n] & 0XFF));
            if (stmp.length() == 1) hs = hs + "0" + stmp;
            else hs = hs + stmp;
        }
        return hs.toUpperCase();
    }

    public static byte[] hex2byte(byte[] b) {
        if ((b.length % 2) != 0) throw new IllegalArgumentException("The length is not an even number");
        byte[] b2 = new byte[b.length / 2];
        for (int n = 0; n < b.length; n += 2) {
            String item = new String(b, n, 2);
            b2[n / 2] = (byte) Integer.parseInt(item, 16);
        }
        return b2;
    }
}
